For several years now, the Kremlin and its allies have courted Euroskeptic political movements in what has been widely seen as an effort to undermine unity in the European Union’s Russia policy -- including sanctions for Moscow’s intervention in Ukraine.
Now, following the stunning result of June 23 "Brexit" referendum, the EU is set to lose one of its strongest proponents of a hard line on Russia, a development that some European officials say threatens the bloc’s resolve in its dealings with Moscow.
"Nobody can imagine that our voice in the European Union will carry weight as of today," British Foreign Secretary Philip Hammond told the BBC on June 24. He said the result of the referendum likely pleased Russian President Vladimir Putin.
"I suspect this morning [Putin] is feeling a little less pressure and he’ll be feeling a bit more upbeat about his prospects of eventually getting these European Union sanctions watered down," Hammond added.
Any impact of the Brexit vote on the EU's policy toward Russia is unlikely to be immediate, experts say. The process of Britain leaving is expected to take two years or more, during which time it will remain an EU member.
EU diplomats, meanwhile, agreed earlier this week to prolong Ukraine-related sanctions targeting Russia by another six months.
But Petras Austrevicius, a liberal member of the European Parliament's Foreign Affairs Committee from Lithuania, said that Britain "has always been a staunch and a very stable partner in terms of shaping the EU's policy toward Russia" and that "any diminishing" of its role in the bloc would negatively impact this policy.
"I believe it was very much in the Russian interest to see Brexit happen. Now we see a reality which is absolutely unfortunate, and this is a great sense of joy in the Kremlin," Austrevicius says. "In general terms, Brexit will in fact make the EU policy toward Russia less effective."
Polish politician Jacek Saryusz-Wolski, a member of European Parliament with the center-right European People's Party faction, says that the EU is more likely to waver on its Russian sanctions with Britain on its way out.
Poland, like Lithuania, is on Russia's western flank and was under Moscow's domain during Soviet times. Both countries are among the most vocal critics of the Kremlin in the EU and NATO.
Saryusz-Wolski says Poland will have "to compensate for the loss of Britain" in advocating for a tougher line on Moscow.
"So [it will be] an even bigger challenge ahead of Poland, an even more difficult task. But we have no choice. We have to live with it," he says.
Some members of the Russian political elite, including Moscow Mayor Sergei Sobyanin, have also suggested that Britain's exit from the EU will soften the bloc’s stance on Russia sanctions.
Putin, however, said on June 24 that he does not believe Brexit will influence EU sanctions policy.
'A Balancing Role'
Relations between London and Moscow remain tense over issues such as Russia’s forcible annexation of Ukraine's Crimea territory and the war between Kyiv and Russia-backed separatists in eastern Ukraine. The 2006 poisoning death of former KGB officer Aleksandr Litvinenko in London, a killing Britain has blamed on a sitting member of the Russian parliament, has also troubled bilateral ties.
The Russian Embassy in London calls the political dialogue between the two countries at the moment "non-existent" and accuses the British government of engaging “in hostile rhetoric” toward Moscow.
Rosa Balfour, a policy analyst from the German Marshall Fund, told RFE/RL that she does not expect significant changes in EU policy toward Russia in the short term, but that Britain’s departure would leave the bloc without London’s "nice balancing role" in the bloc's relations with Moscow.
"It has been firm [on] and critical of Russia but does not have the same existential anxiety that the central European states and the Baltic states have," Balfour said. "And so it will be felt if that element becomes absent."
Sam Greene, director of the Russian Institute at King's College in London, called suggestions by some Russian officials that Brexit would weaken sanctions against Moscow "wishful thinking."
"The reality is, (sanctions) didn't become something that Britain had really strong feelings about…until it was absolutely sure that Germany had strong feelings about it," Greene told RFE/RL. "And the crux of the sanctions regime is the relationship between Washington and Berlin."
U.S. President Barack Obama and German Chancellor Angela Merkel have spearheaded the Western effort to punish Moscow for its actions in Ukraine.
Experts, however, see fissures emerging in Berlin's Russian policy. German Foreign Minister Frank-Walter Steinmeier earlier this week called for greater dialogue with Moscow. His fellow Social Democrat, Vice Chancellor and Minister for Economic Affairs Sigmar Gabriel, is reportedly set to meet Putin in Moscow next week.
"Germany is getting wobbly," Judy Dempsey, a policy analyst with Carnegie Europe, told RFE/RL. "The chancellor has so much stuff on her plate now that the last thing she wants is another problem building up over in Russia."
The Berlin-based Russian political analyst Leonid Bershidsky said on June 24 that "both the immediate matter of sanctions and the long-term state of the EU" -- and the bloc's relations with Washington -- have depended much more on continental powers like Germany than on Britain.
"If the EU becomes more cohesive without the U.K., which often pulled in the other direction, and if the U.S. plays a role, Brexit may end up being a setback for Putin's foreign policy goals," Bershidsky wrote.